1. Field of the Invention
This invention relates to a plasma display panel, referred to hereinafter as a PDP.
2. Description of the Related Arts
PDPs have been extensively employed for monitors of television receivers and computers, and the structures as well as the materials thereof are still further under improvements.
AC type PDPs of three-electrode structure are commercially on production for color display devices. This structure is such that a pair of sustain electrodes is arranged for each line of the display matrix, and an address electrode is arranged for each row of the matrix. Colors to be displayed are determined by controlling the amount of light emitted from respective fluorescent materials of R (Red), G (Green) and B (Blue).
In this kind of PDP is employed as a discharge gas a Penning gas in which a small amount of xenon (Xe) gas is mixed with neon gas (Ne). Upon generating a discharge between a pair of sustain electrodes in pair the discharge gas emits an ultra violet ray. The fluorescent material is excited by this ultra violet lay so as to emit its light. The mixing ratio in the discharge gas is optimized in consideration of the margin of driving voltages, the deterioration of the fluorescent materials and the dielectric protection layer caused by bombardment thereto. The mixing ratio is typically 2 to 10 percent.
As a prior art, it has been known that a helium (He) gas is added into the above-described Penning gas (Ne+Xe). The addition of the helium gas improves the luminous efficiency as well as the color purity.
The increase in the xenon gas content decreases the excited light emission from the neon gas so as to relatively increase light emission of the fluorescent material, resulting in an improvement of the display color purity. On the contrary, the discharge firing voltage increases considerably; therefore, it is impossible to expect a distinct improvement in the color purity within the practical range of driving voltages. Moreover, the xenon gas emitting a near-infrared ray together with the ultra violet ray causes a problem in that the increase of the xenon gas enhances a possibility of disturbing an infrared remote controller of electric appliances or an infrared communication equipment located near the PDP.
On the other hand, there is another problem in that though the addition of helium gas improves the light emitting efficiency as well as the color purity as described above, the further addition thereof accelerates the sputtering of the fluorescent materials and the protection layer, resulting in a short operation life of the PDP. Furthermore, these is a problem of helium lessening the voltage margin of the AC driving voltages. Still more, the effect of xenon gas to suppress the near infrared ray is small, but the addition of helium gas adequate to suppress the near infrared ray considerably shortens the operation life, and the less operating margin makes the driving difficult.